The present invention relates to an improved wellhead seal for sealing across the annulus between the interior of a wellhead housing and the exterior of a hanger positioned within the wellhead housing.
Prior wellhead seals have included resilient seals which are actuated into sealing position by axial force exerted on the seal ring as shown in U.S. Pat. No. 3,492,026.
Other wellhead seals have included resilient material with metal end members having lips which when the seal is set engage the sealing surfaces to prevent the extrusion of the resilient material and also provide a metal-to-metal metal sealing engagement as shown in U.S. Pat. No. 4,496,162.
Some annular wellhead seals have wedging elements to wedge the legs of the seal ring into sealing engagement with their sealing surfaces. U.S. Pat. Nos. 4,131,287 and 4,595,053 disclose such structure and the '053 patent discloses the use of wickers or small parallel grooves into which the seal is forced for sealing.
Further, it has been known to form tubular members into fittings so that they are secured and in sealing engagement with the interior of their fittings. This art is best shown in the U.S. Pat. Nos. 1,905,122; 2,438,529; 2,477,676; 3,432,916; 4,330,144; 4,388,752 and 4,593,448. U.S. Pat. No. 4,593,448 discloses the use of a collapsible material in the grooves to avoid having liquid in the grooves which would prevent the desired forming of the tubular member into both sealing and locking engagement with the exterior fitting.